Replication and transfer of microstructures and nanostructures

ABSTRACT

A method for the duplication of microscopic patterns from a master to a substrate is disclosed, in which a replica of a topographic structure on a master is formed and transferred when needed onto a receiving substrate using one of a variety of printing or imprint techniques, and then dissolved. Additional processing steps can also be carried out using the replica before transfer, including the formation of nanostructures, microdevices, or portions thereof. These structures are then also transferred onto the substrate when the replica is transferred, and remain on the substrate when the replica is dissolved. This is a technique that can be applied as a complementary process or a replacement for various lithographic processing steps in the fabrication of integrated circuits and other microdevices.

RELATED INVENTIONS

[0001] This application relates to, claims the benefit of the filingdate of, and incorporates by reference the United States provisionalpatent applications entitled “Transfer lithography printing strategy”,No. 60/383,275, filed May 22, 2002, “Method and means for templatemanufacture”, No. 60/382,690, filed May 23, 2002, “Lithographic imprintarray method and means”, No. 60/396,705, filed Jul. 16, 2002, “Moleculartransfer lithography method and means from template”, No. 60/401,158,filed Aug. 3, 2002, which are all assigned to the assignee of thepresent invention.

[0002] The invention was made with government support under Grant(Contract) No. N66001-01-1-8962 awarded by the Defense Advanced ResearchProjects Agency (DARPA). The government has certain rights to thisinvention.

FIELD OF THE INVENTION

[0003] This invention relates to a new process for the replication ofsurface relief at the micrometer and the nanometer dimension scale.Furthermore, the process provides for the transfer of the replicatedpattern from a master substrate to a second substrate. This inventiondescribes a method of transfer lithography in which a disposableintermediate template is used. The process is also suitable forreplicating and/or transferring single or multiple layers of microscopicelements that are to be used for photonic applications, metrologyapplications, and in the fabrication of integrated circuits and othermicrodevices.

BACKGROUND OF THE INVENTION

[0004] Microlithographic patterning of integrated circuits has madegreat improvements in the recent years. Prototype devices withdimensions less than 100 nm in width have been demonstrated, and areexpected to enter routine production soon.

[0005] These integrated devices are typically assembled sequentially,through a series of process steps that carry out the necessarydeposition, patterning, and etching steps that result in the finaldevice. A contemporary microdevice often comprises more than 25 distinctlayers, each with its own mask to define feature dimensions, and asequence of process steps that the entire wafer must undergo to createthe desired layer.

[0006] Extremely high resolution lithography can be carried out usingelectron beam (or E-beam) lithography. This prior art technique forfabricating microdevices is illustrated in FIG. 1. In this example, thepartially processed device 100, comprising a substrate 110 with thepreviously fabricated layers 120 containing microstructures 112 and 122,is coated with a uniform layer 130 of the material to be processed (e.g.metal, polysilicon, etc.), and then coated with a polymer layer 150,commonly called a resist, sensitive to electron beam exposure. Thesensitive layer 150 is then exposed to patterns of electron beams 160,as shown in FIG. 1a, where the geometric arrangement and dose definesthe pattern to be formed. The exposed material is then chemicallyprocessed, or developed, and, as shown in FIG. 1b, the unexposed regions152 are left on the substrate. These serve as protection for portions ofthe material to be patterned 130, so that after subsequent processing,as shown in FIG. 1c, only the protected portions 132 of the material 130to be processed remain.

[0007] Although E-beam lithography can produce extremely high resolutionpatterns, the typical throughput of an E-beam machine is very slow.Beams must be directed to each spot on the wafer in sequence, whichmakes the process generally slow and impractical for large numbers ofmicrostructures. Instead, in optical lithography, the E-beams 160 arereplaced by an optical image of a mask, which exposes the sensitive film150 in parallel. However, optical imaging techniques do not have thesame resolution as E-beam systems, and fabricating nanostructures(features with dimensions on the order of 100 nm or smaller) in theselayers has been growing exponentially more expensive. As a result,alternative paradigms for lithography of these layers have beeninvestigated.

[0008] One example of these novel technological patterning paradigms isnanoimprint technology. In nanoimprint techniques, a master pattern isformed by a high resolution patterning technique, such as E-beamlithography. These high resolution masters are then used to create acorresponding pattern on the IC layer without the use of an imagingstep, but with some kind of stamping or printing technique. This is inprinciple very similar to techniques used for creating the microscopicpatterns found on compact discs (CDs).

[0009] The most straightforward illustration of this was developed byStephen Chou et. al, and is illustrated in FIG. 2. Chou's process wouldtake the same layer to be processed 130, coated on a partiallyfabricated substrate 100, but coat the assembled substrate with a layerof a deformable polymer 250, as shown in FIG. 2a. The master template210, with patterns of indentations 212 corresponding to locations wherethe final structures are desired, is fabricated by high resolutionlithography techniques. The template 210 is then aligned over thesubstrate 100 and as shown in FIG. 2b, the two are pressed together. Thedeformable polymer 250 fills the indentations 212 in the master 210. Themaster is then removed, leaving a pattern of structures 252 on thesubstrate 100 as shown in FIG. 2c. Subsequent processing, such asetching, leaves the desired result of patterns 132 formed from layer130, defined by the locations of the remaining material 252, as shown inFIG. 2d. Chou has demonstrated the reproduction of features as small as10 nm using this technique.

[0010] C. Grant Willson et al. have proposed a variation on thistechnique as illustrated in FIG. 3. In this approach, the master 310 istransparent to ultraviolet light. This master 310 also containsindentations 312 patterned in the surface through a high resolutionfabrication technique. As shown in FIG. 3a, Willson's process takes thesame layer to be processed 130, coated on a partially fabricatedsubstrate 100, but coats the assembled substrate with a layer of adeformable polymer 350 which is also sensitive to UV exposure. Thetransparent master 310 is pressed against the polymer 350 on layer 130and substrate 100. This layer 350 deforms, filling the indentations 312in the master 310 with material 352., while possibly leaving a thinlayer 351 still between the surface of the master and the substrate. Thepolymer materials 351 and 352 are then cured and hardened using UVexposure 360, as shown in FIG. 3b. Then, as shown in FIG. 3c, the masteris removed, and leaving thicker material 352 over the portions of layer130. Subsequent processing, such as etching, leaves the desired resultof patterns 132 formed from layer 130, defined by the locations of theremaining material 352, as shown in FIG. 3d.

[0011] A drawback to these techniques is that the master must berepeatedly used again and again in the formation of the desiredmaterial. This can lead to damage to the master through normal wear andexposure to contaminants. A common technique used to replicatediffractive structures used for gratings and other photonic devicesinvolves the creation of replicas of a master grating. These methodsinvolve the creation of a master from which replications are made byapplying a thin vacuum deposited separation layer on the master. A metalcoating is then deposited on top of the separation layer, and an epoxycoated substrate is placed on top of the layer-covered master. Thecombination is then cured and the process is completed when thereplicated grating is separated from the master grating. This approachsuffers from throughput limitations requiring vacuum depositions on themaster. With this approach, the master suffers degradation only from thecreation of multiple replicas; the replicas themselves are used in theactual fabrication process and are discarded when damaged.

[0012] George Whitesides et al. have developed a similar process using areplica, or template, made from poly(dimethylsiloxane) (PDMS) forapplications what he calls “soft lithography”. They have also developeda variation of this process using an inking technique, to minimizedamage to the template. This is similar in concept to the inking ofrubber stamps commonly used in other conventional printing applications.

[0013] An example of this process is illustrated in FIG. 4. The master400 with indentations 402 itself is not used directly, but is replicatedas a polymer template 410 with raised sections 412 corresponding to theindentations 402. This polymer template 410 can be used directly forimprint lithography, and discarded if damaged through reuse. To achievethe same patterns 132 from a layer to be processed 130, coated on apartially fabricated substrate 100, Whitesides' process coats theassembled substrate with a layer of a special material 450 which isselected for certain chemical characteristics. As shown in FIGS. 4a and4 b, the template 410 is formed from PDMS by coating the master 400 withthe material, either through spin coating or by some other coating andcuring technique. Then, as shown in FIG. 4c, the template 410 is thenbonded to a carrier 430 using some bonding layer 420, and removed fromthe master 400.

[0014] This template 410 is then “inked” with a thin layer of specialchemicals 414 such that only the raised portions 412 of the template 410are coated with the chemical 414, as shown in FIG. 4d.The template isthen aligned and placed in close contact with the substrate 100 withpartially fabricated microdevices also coated with a layer to beprocessed 130 and chemical layer 450, transferring the “ink” 414 to thesubstrate as shown in FIG. 4e The material for the ink 414 and the layer450 will be chosen to react, and leave an altered layer of material 452in locations touched by the ink 414, as illustrated in FIG. 4f. Thisaltered material 452 serves as a barrier to the reactions, protectingthe layer 130 below. Subsequent processing leaves the desired result ofpatterns 132 formed from layer 130, defined by the locations of thealtered material 452, as shown in FIG. 4g

[0015] Some of the problems with PDMS as a template that limit itsapplicability include limited resolution (about 200 nm) because of thedifference in thermal expansion coefficient between the PDMS and themold material, and limited throughput because of the time needed forcuring. It also suffers from material incompatibility since it willstick to large areas of clean silicon.

[0016] In all of these fabrication techniques, the imprinting techniqueserves as a method for pattering a layer or film directly on the finalsubstrate, e.g. a silicon wafer. The imprint master or template is usedagain and again to stamp out duplicate copies of nanostructures at lowcost.

[0017] There can be undesirable consequences from using thesetechniques. For example, the definition of a particular layer withextremely fine structures with E-beam exposure will inherently riskirradiating the underlying layers to the electron beam as well. Caremust be taken to insure that the electrical structures already createdin the underlying layers are not damaged. The mechanical stamping of themaster or the template onto the substrate must also be preciselycontrolled, or the fragile structures underneath can be strained orcracked. Keeping the master or replica free of defects as it is usedagain and again can also present problems.

[0018] Furthermore, processing the wafer itself layer by layer, althoughthe standard fabrication technique for integrated circuits, may be lessthan optimal. For example, a metal or polysilicon layer may be bestprocessed at a high temperature for the best results, but this degree ofheating may damage or even melt the layers previously prepared on thesubstrate. Because all subsequent steps in the manufacture of themicrodevice are deposited on the same substrate, however, these problemsin process compatibility and their required compromises remain.

[0019] Some manufacturing processes in other industries avoid theseproblems by having separate manufacturing processes for differentcomponents, and then assembling these at a later stage of integration.The packaging of ICs is one example of such a dual process, in which theIC itself is prepared on a silicon wafer, and then cut from the waferplaced and bonded into a pre-prepared package. The preparation of thepackage and the IC follow two separate manufacturing processes until thebonding step is required.

[0020] Another example of this kind of dual processing or patterning isfound in the common sticker. A pattern in ink is prepared on paper,plastic or some other substrate, and an adhesive applied that allowsbonding to another substrate. Examples of this are very common, forexample, as decorations in a scrapbook, as a label on filing cabinet, oras a statement on an automobile bumper. Clearly, forcing a large objectsuch as an automobile bumper to fit through a printing and patterningprocess to attach a simple humorous message would be awkward and veryexpensive. The bumper sticker is far more flexible and far lessexpensive.

[0021] Likewise, the separation of substrate preparation and even thefabrication of microstructures can be commonly seen. Embossed holograms,such as those found on common credit cards, have structures with sizeson the same order of magnitude as the wavelength of visible light(400-700 nm). These are easily created using a printing or mechanicalstamping process, and can also be prepared with adhesives. They are thenand attached to many other substrates, such as credit cards, bumperstickers, magazine pages, etc. that could not be used directly in aholographic fabrication process themselves. Integrated circuitsthemselves are also finding application when attached directly on thesurface of various “smart cards”.

[0022] In a previous invention, described in US patent applicationentitled “Molecular Transfer Lithography” and assigned Ser. No.09/898,521, we have disclosed an invention separating the preparationand imaging in lithographic materials, and the subsequent steps ofprocessing the image and transferring the pattern into the finalsubstrate. This was done by the formation of the required latent imagein photoresist on an intermediate carrier. The photoresist containingthe latent image is then mechanically aligned and transferred to thelocation on the final substrate where the subsequent processing is tooccur.

[0023] This separation of processing steps allows an inventory ofpre-processed latent images to be formed that can be used upon demandwithout delay. These latent images are typically formed on flat carriersunder optimized imaging conditions. It also allows the preparation to becarried out on the carrier using an optimized process without concernfor the immediate consequences on the substrate, since the substrate isnot part of the process. The only concern would be the interaction ofresidues and the substrate once they are brought together.

[0024] Although the prior techniques reflect a great degree ofinnovation and creativity, and can offer significant cost advantagesover conventional lithographic processing techniques, there is a needfor a technique that has many or all of the advantages of a nanoimprinttechnique but does not have the problems associated with reusing amaster or template. Furthermore, although the previously disclosedmolecular transfer lithography technique addresses some of these issues,the latent image formed was generally flat and did not have topographicstructures corresponding to the topography desired on the final wafers.

SUMMARY OF THE INVENTION

[0025] We disclose here a method of replicating microstructures ornanostructures from a master, processing the replicated structures, andtransferring them using a dissolvable template. This dissolvabletemplate is not reused to pattern several substrates, but is physicallytransferred to a substrate for pattern definition, and subsequentlydissolved.

[0026] Furthermore, we disclose here a method for pre-processingmaterials on the replica which are then transferred to the substrate,instead of conducting all processing on the final substrate itself.

[0027] We also disclose a method of actually fabricating layers orportions of layers of a microdevice on the replica, and transferringthese pre-assembled elements or nanostructures to the final substrate.

[0028] To implement this method, we create a master pattern using a highresolution lithographic technique, such as electron beam lithography, ona durable substrate, such as silicon or quartz. Typically, this masterpattern will have some definition of the features to be created asvariations in topography, and may be identical to the master patternsused in other nanoimprint lithography techniques.

[0029] The patterns on the master are then replicated by one of avariety of processes onto a template, supported by an intermediatecarrier. The template can serve merely as a disposable replica of themaster for subsequent use in an imprint lithography system, or can serveas the basis for the formation of the nanostructure elements themselves.These nanostructures may be created on the carrier through the suitablesequence of deposition, electroplate, coating, patterning, and/oretching steps. The selection of processing details will depend on thespecific application for the final device. Aside from micro andnanostructures for electronic devices, the template may be used tofabricate a diffraction grating or other photonic device depending onthe desired application. Other applications are micro electro mechanicalsystems (MEMS), superconducting devices, and biological applicationsinvolving selective patterning of protein and DNA sequences.

[0030] Once the template is attached to the carrier, the carrier can bestored until it is required for manufacturing. At that time, it isaligned to the final device substrate and facilitates the transfer ofthe pattern. The template may be adhered to the surface directly or maybe applied using a form of imprint lithography. However, the key elementof our invention is that the template is actually transferred to thesubstrate and the carrier removed, leaving the template on the substratefor subsequent processing. The template is destroyed by this subsequentprocessing.

[0031] With inexpensively made templates, this disposable templatetechnique offers all the advantages of nanoimprint lithography, whileeliminating the problems that occur through template reuse. Once thetemplate is created; however, it is clear that additional processing cantake place on the template prior to the transfer. This can be as simpleas coating to aid in a possible subsequent transfer or nanoimplintprocess, or the application of coatings to allow the template itself tobecome a optical component such as a polarizer or fresnel lens.

[0032] However, it is also possible to carry out a more elaboratesequence of processing steps on the template, actually pre-fabricatingelements of components such as nanoscale wires or contacts that can betransferred directly into the final devices. These can then betransferred along with the dissolvable template, using a direct transferfrom a carrier to a substrate, as part of the manufacturing process forthe final device, or can be transferred as a nanoimprint process iscarried out.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1: FIG. 1: Processing steps for pattern formation by E-BeamLithography (Prior Art).

[0034]FIG. 2: Processing steps for pattern formation by the nanoimprinttechnique of Chou (Prior Art).

[0035]FIG. 3: Processing steps for the step and flash process of Willson(Prior Art)

[0036]FIG. 4: Processing steps for the microcontact printing ofWhitesides (Prior Art).

[0037]FIG. 5: Flow chart of generic process according to the invention.

[0038]FIG. 6. Processing steps for a nanoimprint process using adissolvable template according to the invention.

[0039]FIG. 7: Representative flow chart for additional processing on thetemplate.

[0040]FIG. 8: Representative flow chart for the creation ofnanostructures on the template.

[0041]FIG. 9: Processing steps for the preparation of masters.

[0042]FIG. 10: Additional processing steps for the preparation of amultilayer master.

[0043]FIG. 11: A conventional spin coating apparatus.

[0044]FIG. 12: Processing steps for using a pre-formed disk.

[0045]FIG. 13: Process steps for sputtering onto a template and ananoimprint process using that template.

[0046]FIG. 14: process steps for preparing patterned materials on atemplate and transferring the patterned materials to a substrate.

[0047]FIG. 15: Process steps for preparing nanostructures on a templateand transferring the nanostructures to a substrate.

[0048]FIG. 16: Alternative processing steps for preparing patternedmaterials on a template and transferring the patterned materials to asubstrate.

[0049] Note: All drawings in cross section are for illustration purposesonly. The dimensions of the layers in these illustrations are not shownto scale, nor should any conclusion about the desired relative thicknessof the layers be drawn from these illustrations.

[0050] Note: Although we have used identical numbers to represent apre-formed substrate 100 and its elements, as well as layer 130 on thissubstrate representing the layer of material to be processed, it will beclear that any substrate with any number of preformed layers can be usedwith this technique.

DETAILED DESCRIPTION OF THE INVENTION

[0051] As indicated above, this represents a manufacturing technique forintegrated devices using a dissolvable template that is low cost, andcan be applied to nanoimprint techniques or to the pre-fabrication ofportions of microdevices that are stored until their use is required. Wenow present a more detailed description of the best and preferredembodiments of the invention.

[0052]FIG. 5 shows a flowchart for a manufacturing process using thistechnique. Initially, as shown in FIG. 5a, step 500 creates a masterpattern defining the layout of the structures to be fabricated. Step 510represents the replication of the master in a template. Step 520represents the transfer of the template to a carrier. In step 530,optional additional processing steps are carried out on the template.This is also the step where entire nanostructures or portions of otherdevices can be fabricated on the template. In step 540, the carrier andtemplate, along with any structures fabricated on the template, areplaced into storage.

[0053] In step 550, initial layers are fabricated on the substrate untilthe point is reached where the patterning corresponding to thepre-fabricated template is required. In step 560, the carrier/templateis removed from storage, and in step 570 the carrier is aligned to thesubstrate. In step 580, the template is transferred to the substrate andthe carrier removed. This step can comprise a nanoimprint transfermethod, or can also comprise a simple mechanical transfer facilitated byadhesives. Finally, in step 590, the substrate and template undergoprocessing which destroys the template and leaves the desired patternson the substrate.

[0054]FIG. 6 shows a more detailed sequence of steps for the mostgeneral form of the process as we have implemented it in our laboratory.The master pattern is created as raised portions 612 on a substratematerial 600 as shown in FIG. 6a by a precise high resolutionlithographic technique, typically using E beam lithography. Typically,material for the master 600 will be a rigid material such as silicon,although transparent materials such as quartz can also be used.

[0055] The template 600 with raised structures 612 is then created bycoating the master with a conforming coating 610. A typical material forthis is polyvinyl alcohol (PVA). This results in a coated master, asillustrated in FIG. 6b. This material is applied from solution by spincoating, and the resulting template 610 fills the topographic contoursof the master 600 while leaving a back surface that is uniformly flat.

[0056] The template 610 is then removed from the master 600 and attachedto a carrier 630, typically with a pre-formed sheet 620 to aid adhesion.The sheet 620-is connected to the carrier 630, made for example from apolyolefin sheet, with a suitable adhesive 625. The removal andattachment steps can actually be combined, by having a carrier 630 withadhesive 625 placed in contact with the back of the template 610 andremoving them together.

[0057] The carrier 630 with template 610 is then stored until amicrodevice on a substrate 100 is processed to the point where a layer130, as shown in FIG. 6d, requires patterning using the layoutcorresponding to the indentations 612 on the master 600.

[0058] The substrate 100 with layer 130 is then prepared for transfer bycoating with an deformable layer 650. This layer may be fabricated fromthe same material used to make deformable layers 250 or 350 in othernanoimprint processes, but can also be another material. The carrier 630with the appropriate template 610 is removed from storage and alignedwith the substrate 100, as shown in FIG. 6e. The carrier 630/template610 is then pressed against the deformable layer 650 layer on thematerial 130 and substrate 100, according to normal nanoimprinttechniques. The deformable material 650 deforms to fill the indentations612 in the template 610, forming patterned material structures 652. Thecarrier 630 is then removed, leaving the template 610 and patternedmaterial structures 652 behind, as shown in FIG. 6f. The substrate 100with template 610 is then processed in a manner which dissolves thetemplate 610 and sheet 620. Typically, this isby immersion in water,which dissolves PVA. After the template 610 and the preformed sheet 620dissolve, the patterned material structures 652 on portions of the layer130 to be patterned remain, as shown in FIG. 6g. Subsequent processingsuch as etching transfers this pattern to the material layer to bepatterned, as shown in FIG. 6h.

[0059]FIG. 7 shows a flow chart for a variation of this process, inwhich additional processing steps are carried out. For this example, theoptional processing step 530 from FIG. 5 comprises steps 732, 734, and736 in which a special barrier layer or layers are coated onto thesurface of the template and processed. This can protect the template 610from contamination during storage, or have other desired chemical andphysical effects. One option for the formation of the barrier layer isthat the surface of the template 610 is coated with a metal, such asgold, using a sputtering system, shown as step 732. Typical coatinglayers are on the order of 10 nm thick, although the exact thicknesswill vary depending on the sputtering conditions. This can further becoated with a polymer layer in step 734 for additional protection. Instep 736, the polymer layer can undergo further processing, such asplanarization.

[0060] It can be seen that this process, in which the deposition of ametal layer in step 732 (in this case gold) as a barrier layer, can bealtered to be create thicker structures as well. The flow chart for thisaltered process is shown in FIG. 8. For this example, the optionalprocessing step 530 from FIG. 5 comprises steps 832, 834, 836, and 838in which nanostructures are formed on the surface of the template andprocessed. This may be especially effective if, for example, thedeposited metal is copper, and of suitable layouts and dimensions toform the interconnect layers (or portions thereof) of an integratedcircuit.

[0061] In step 832, a coating of material suitable for the fabricationof the nanostructures of a layer of a microdevice is deposited on thetemplate. This would be a material for example that corresponds to thematerial layer 130 used in the other examples of this application. Thiscan be a simple deposition process, or in turn may comprise many processsteps, such as the initial sputtering of a seed layer, followed by thegrowth of a thicker film through electroplating. In step 834, additionalprocessing can be carried out, which can include coating the metal witha polymer. In step 836, the combined materials can be further processed,e.g. with an etching or polishing process, so that certain portions ofthe coated metal are then exposed, while other portions are remainprotected. An additional step 838 may then also be executed to protectthe exposed material for storage.

[0062] Once created, these micro or nanostructures are transferred alongwith the dissolvable template in step 580. This step can comprise ananoimprint transfer method, or can also comprise a simple mechanicaltransfer facilitated by adhesives.

[0063] We now describe each of these steps in more detail.

[0064] Creation of the Master

[0065] The initial step in this process is the creation of the originalmaster containing the layout pattern. The essential element in thepatterning of the master is that it comprises a layout of the structuresto be replicated in a reproducible form. This is most simply done byforming the layout as a relief pattern on a rigid substrate. The reliefpattern can be created by patterning and selectively etching a rigidmaterial, such as a silicon wafer, or by patterning a material depositedon the rigid substrate, such as a chrome/chrome oxide layers on quartz(a conventional photomask blank). Although a disc shaped master hascertain advantages for processing, masters of other shapes, such assquares, rectangles, hexagons, octagons, etc. can also be used.

[0066] The master can be fabricated using conventional microfabricationor nanofabrication techniques. The preferred method involves the use ofa direct-write E-beam lithography system to expose patterns inphotoresist on a silicon wafer, because of its high reliability and highresolution. This is illustrated in FIG. 9. In this process, anunpatterned material 900 (also sometimes called a “blank” is coated witha layer 910 polymer material, commonly called a resist, sensitive toelectron beam exposure. The sensitive layer 910 is then exposed topatterns of electron beams 960, where the geometric arrangement and dosedefines the pattern to be formed, as shown in FIG. 9 a. The exposedmaterial of layer 910 is then chemically processed, or developed, and,the unexposed regions 912 are left on the substrate, as shown in FIG.9b. These serve as protection for portions of the blank 900, so thatafter subsequent processing, for example by etching, the protectedportions remain as raised portions 602 while the rest of the materialsurface has been etched. This creates a master 600 with topographicstructures 602 corresponding to the layout pattern of the exposure 960,as shown in FIG. 9c.

[0067] There are alternatives to electron-beam lithography to create amaster with relief for replication. For example, one could use anoptical lithography system with a mask to expose the initial pattern.Other methods include EUV or x-ray lithography or nanoimprintlithography. In fact, any lithographic technique could be used tofabricate the master as long as the process had suitable resolution andaccuracy.

[0068] Although silicon is a convenient material to use for the master,there are many materials that could be used for the master other thansilicon. Semiconductors that have well known patterning processes suchas silicon, germanium, GaAs, SiGe, Silicon-on-insulator (SOI), GaN, GaP,InP, etc. can also be used as blanks. Metals such as stainless steel,iron, copper, or aluminum could also be used as blanks. Since only thetopographic structure on the substrate is transferred, one could coatany rigid material with a polymer such a photoresist, expose and developthe photoresist, and use the resulting relief pattern as the masterrather than go through the subsequent etching and stripping steps forthe blank material. There are many well known processes for photoresistthat can leave topographic profiles of various kinds.

[0069] Another material suitable for a master are quartz or glass platescoated with chromium/chrome oxide materials that form the opaque layerof a conventional photomask. This can be especially useful if asubsequent step requires exposure through the master for UV curing. Thisis illustrated in FIG. 9 as well. An unpatterned material 930 coatedwith a layer of opaque material 940 (in this case, the combination of930 and layer 940 is sometimes called a “blank”) is coated with a layer950 of a polymer material, commonly called a resist, sensitive toelectron beam exposure. The sensitive layer 950 is then exposed topatterns of electron beams 970, where the geometric arrangement and dosedefines the pattern to be formed, as shown in FIG. 9d. The exposedmaterial of layer 950 is then chemically processed, or developed, andthe unexposed regions 952 are left on the blank, as shown in FIG. 9e.These serve as protection for portions of the layer 940, so that aftersubsequent processing, for example by etching, the protected portionsremain as raised portions 942 while the rest of the material surface hasbeen etched. This is illustrated in FIG. 9f. This creates a master 930with topographic structures 942 in opaque material corresponding to thelayout pattern of the exposure 970.

[0070] Typically, the layer 940 can be manufactured from a mixture ofchrome and chrome oxides typically and sold as photomask blanks.However, other materials, such as aluminum or gold, could also be chosenas ingredients in layer 940 for their particular thermal, electrical, orchemical properties. Likewise, the underlying substrate material 930 ofa photomask blank is typically quartz, but other transparent materialssuch as glasses, hardened polymers, or transparent crystals such as CaF2can be used for substrate 930 as well. For situations sensitive todimensional change from temperature control, a material with a lowthermal expansion coefficient such as Zerodur can be used for thesubstrate 930. One could also form or coat a thin-film material on topof the relief pattern to aid in subsequent processing steps.

[0071] The relief pattern can also be created by etching the rigidsubstrate of a quartz master directly. This can be done using commonlyused lithography techniques for photomasks, and etching procedures tocreate topographic structures for phase-shifting masks. Such processingsteps can be based on wet etching, in which the exposed surface isselectively removed through a reaction with a liquid chemical such asthe quartz etchant hydrofluoric (HF) acid, or a dry etching proceduresuch as reactive ion etching (RIE) in a suitable plasma chamber. Otheretchants specific to various other rigid substrate materials, such asthe semiconductor materials listed above, can also be used.

[0072] It may be desirable to have a multi-level master, in which theseveral levels of topography are defined. This is illustrated in FIG.10. This can be accomplished through a second set of lithographicexposure and development steps. Although E-beam lithography may be thepreferred technique, it is easily recognized that any lithographicpatterning step that can be aligned with the initial set of structurescan be employed as well.

[0073] An example of this sequence is shown in FIG. 10. For thisprocess, the original steps shown in FIGS. 9a-9 c are executed to createa master 600 with a set of topographic patterns 602. This master 600 isthen coated with another layer of a sensitive polymer 1010, commonlycalled a resist, sensitive to electron beam exposure. The sensitivelayer 1010 is then exposed to a second pattern of electron beams 1060 asshown in FIG. 10a, where the geometric arrangement and dose defines thesecond pattern to be formed. The exposed material of layer 1010 is thenprocessed, or developed, and the unexposed regions 1012 are left on themaster 600, as shown in FIG. 10b. These serve as protection for portionsof the master 600, so that after subsequent processing, for example byetching, the protected portions 602 and protected indentations 1002remain unaffected while the rest of the material surface has beenetched. This creates a master 1000 with multi-layer topographicstructures, as shown in FIG. 10c.

[0074] Although this has illustrated only a two-step process, it will beclear that this can be applied an indefinite number of times, with anindefinite number of arbitrarily defined layouts.

[0075] Although we have practiced this invention with masters formed onrigid substrate materials, it is clear to those skilled in the art thatvarious degrees of rigidity may be allowed for different fabricationtolerances, and that flexible substrates with topographic structures mayalso be prepared to form masters for certain applications.

[0076] It will also be clear that any lithographic technique amenable tomultiple exposure can be employed here as well. Although we havepatterned our masters using silicon wafers and conventional e-beamlithography, extremely high resolution structures (e.g. 10-100 nm insize) can be obtained using X-ray lithography, EUV lithography, and evenvariations of optical lithography with a suitably high NA and theapplication of various resolution enhancement techniques. Evennanoimprint techniques can be used to fabricate the master.

[0077] Replication of the Master and Creation of the Template

[0078] Once the master has been created, the template that replicatesthe structures on the master must be created. This can be done by avariety of molding techniques, most of which comprise pouring a liquidon top of the master and allow the material to dry or harden. The mainrequirement is that the material be able to adequately fill thenanoscale topography structures on the master without the formation ofbubbles or other voids between the master and the coating. Other desiredproperties include the ability to smoothly detach a smooth detachmentfrom the mold, and the ability to prevent the introduction of foreignsubstances, i.e contaminants such as dust, that may introduce flaws.Still other desired properties include the ability to smoothly detachthe template from the mold quickly for high throughput, and the abilityto dry the mold without introducing thermal or mechanical distortions aspart of the drying or curing process for good yield.

[0079] Many techniques can be used for this purpose, including spincoating, spray coating, droplet injection, puddle formation,electrodeposition techniques, etc. Spin coating has proven a veryeffective technique for creating thin conforming films. Typical spincoating is illustrated in FIG. 11. For spin coating, the master 900 ismounted on a chuck 1120 using a vacuum system 1110. A housing 1100containing a motor spins the chuck and the master at various speeds,typically a few thousand RPM. Liquid material or solutions 1130 of thematerial to be molded can be poured from a container 1140 onto thesurface of the spinning master. Excess material 1150 is thrown off thespinning master by centrifugal forces, leaving only a thin layer on thesurface of the master. The residual solvent in this layer quicklyevaporates, leaving only a thin layer of the molding material.

[0080] Alternatively, if a liquid material is used, spin coating may beused to create a uniform conformal coating, and the casting material maybe polymerized or hardened with subsequent processing, or with reactionswith the oxygen or other ambient gasses.

[0081] A material we have found that works well with this technique ispolyvinyl alcohol (PVA). PVA is a water soluble compound, and sosolutions can be created using purified water. Typical solutions can beobtained from a distributor such as Fiberlay of Seattle, Wash., USA, andsold under the brand names of Fiberlease or Partall Film #10manufactured by Rexall. We have found the material of Fiberlease to workexceptionally well. The concentrations of Partall Film #10 in the RexallMSDS are water (56-61%), ethyl alcohol (31-34%), Acetic Acid EthenylEster, Polymer with Ethonol (7-8%), and butyl alcohol (1-2%). Thematerial is usually used as a release layer for molding applications.

[0082] The PVA solution is then poured onto the spinning master, usingfor example spin speeds of 1800 RPM and 15 seconds on a conventionalspin coater. If thicker films are desired, the procedure may berepeated, or slower speeds may be used. The resulting structures conformvery well to the topographic structures on our masters, even fordimensions as small as 40 nm laterally. We have found that thethree-dimensionally replication ability is excellent, that is theability to replicate the pattern in the vertical dimension replicated towithin 20 nm of 100 nm steps, and perhaps better, limited by our presentability to measure. The ultimate lateral resolution we have observed isnot limited by the PVA, but rather by our ability to reliably fabricatestructures this small in the master. Smaller structures can clearly becreated in PVA.

[0083] An additional property of the PVA film is that, while the surfacein contact with the master conforms to the topography of the master, theremaining film can be thick enough that the top surface remains uniform,i.e. does not vary with the underlying topography. The thickness can beadjusted by varying the concentration of the solution, by using solventswith different vapor pressures, by changing the spin speed, or bycontrolling the properties of the environment in which the coating takesplace. Maintaining a contaminant free environment with temperature andpressure control allowing the best solvent evaporation conditions isimportant for ideal replication of the structures on the master.

[0084] Once the conforming layer has been created on the master, it mustbe removed. For thicker PVA films, the layer can simply be peeled off.This free-standing film, however, is usually only a few tens of micronsthick, and can be delicate and difficult to store control.

[0085] Consequently, we have also used pre-formed discs of PVA to assistwith the removal of the spin-coated PVA from the master. Pre-formeddiscs of PVA are commercially available from companies such as Shercon,Inc., of Santa Fe Springs, Calif. A process using these is illustratedin FIG. 12. In FIG. 12a, a master 600 with topographic structures 602has been coated with a PVA film 610 by spin coating. This master isshown as being the master 600 of FIGS. 6 and 9, but can also be replacedby any master, including those shown as 1000 in FIG. 10. A pre-formeddisc 1210 of PVA mounted to a carrier 1230 with a suitable adhesive 1220is then aligned with the master. This disc 1210 can be manufacturedusing a casting method on a flat surface, for example. Such a disc isgenerally packaged with an adhesive backing 1220 connecting the disc1210 to a clear plastic flexible sheet 1230. This form is convenient forremoval of the molded PVA from the master 900.

[0086] In this embodiment of the invention, a master 600 coated with aninitial dried film of PVA 610 is again spin-coated again with anadditional layer of PVA 1205. Immediately, before the solvent iscompletely dried from the additional layer 1205, the pre-formed PVA disk1210 mounted to the carrier 1230 with an adhesive 1220 is placed on thecoated master 600 with PVA, as shown in FIG. 12b. After a drying periodof a minute or more, the structures 1200, 1205, and 1210 bond together,forming structure 1208. This dried structure 1208 is removed from themaster, producing the result shown in FIG. 12c. This structure wouldalso correspond to the pair of structures 610 and 620 shown in FIG. 6.

[0087] More generally, the carrier 1230 need not be a polymer film, butcan be any material with a flat surface of the size and shape suitablefor the size and shape of the layout on the master is created. This canbe made from metal, quartz, a polymer, or any other material that can bestored without contaminating the film once transfer has occurred. Anysolid and/or flexible material can serve this purpose, as long as it iscoated with a suitable adhesive 1220 that allows the PVA coating to beremoved from the master.

[0088] Creation of Structures on the Template

[0089] Once the PVA film that replicates the topography on the masterhas been created and attached to a carrier, material processing on thisreplicated structure or template can be carried out. This can be one ofa variety of steps and will depend on the application. The requirementsfor the subsequent processing on PVA is that (1) no reaction occurs withthe PVA film, and (2) the processing steps not exceed a thermaldecomposition temperature of the PVA film, roughly 230C. Other templatematerials may have other physical and environmental requirements,depending on their material properties.

[0090] In one application, the PVA film may be coated with a metal film.This may be a simple coating to protect the template from contaminationor decay.

[0091] A common process operation that works well with PVA is sputteringor evaporation of metal films. This is illustrated in FIG. 13. In asputtering system, typically in a well controlled vacuum environment1399, a target 1390 of the material desired provides a source for atomsor particles 1392 of the material to be deposited as a layer 1302 on thesurface of the template 1208, mounted to a carrier 630. This isillustrated in FIG. 13a.

[0092] Once the film has been created, the carrier 630 with the template1208 and film 1302 is removes, and can later be used for normal imprintlithography, as illustrated in FIGS. 13b-e (similar to the steps shownin FIG. 6).

[0093] Sputtering tools are commonly available in processing labs, suchas the Stanford University Nanofabrication Facility, or can be obtainedcommercially such as the sputter coater from Cressington ScientificInstruments, Inc., and distributed by Ted Pella, Inc. We have sputteredmaterials onto topographical PVA that include gold, copper, aluminum andchrome using simple sputtering tools. Other materials that can besputtered or evaporated onto PVA include tungsten, Palladium, Platinum,Nickel, Nickel-Chromium. One can also evaporate materials such asCarbon. One can also perform a co-evaporation of superconductormaterials such as Yttrium, Barium, and Cobolt.

[0094] Other methods of depositing films other than byevaporation/sputtering and still satisfy the requirements includechemical vapor deposition by hot filament methods. In these techniques,organic films can be deposited by passing an organic precursor vaporthrough a hot filament where it undergoes thermal fragmentation. Thesubsequent vapor products deposit in solid form on the PVA surface. Withthis method it is possible to keep the PVA at a low safe temperatureduring the film forming process. This method is commonly referred to assolventless deposition of photoresists, such as PMMA (poly methylmethacrylate).

[0095] Another method is through plasma enhanced chemical vapordeposition (PECVD) of thin films as long as the surface temperature isbelow the decomposition temperature of PVA. PECVD films are oxides,nitrides, oxynitrides, polysilicon, fluropolymers, and so forth.

[0096] Spin-coating of materials onto the PVA topographical can also beperformed provided that the liquid not react or dissolve the PVAstructure. Hence the material selection is limited to generallyhydrophobic materials such as fluorine based compounds, for example,that do not have solvents that will react with PVA.

[0097] Further Processing of Structures on the Carrier

[0098] It may also be possible desirable to perform additionalprocessing on the template. The layer on top of the PVA relief providesa convenient coating for the further development, and aids inflexibility since the subsequent processing steps will not interactdirectly with the delicate PVA material.

[0099] It may be desirable, for example, to use the PVA reliefstructures to actually preprocess a photoresist material. This materialwould then be transferred, along with the template, to the finalsubstrate. To create a planar surface, at least two approaches may beused. The first involves spin-coating or depositing using other means anorganic etch-resistant material such as photoresist on the barrier layer1302. This material can form a thick coating that may be thinned usingsubsequent etching techniques.

[0100] This is illustrated in FIG. 14. In this FIGURE, a barrier layer1302 is created from a sputtering source 1390 on a carrier 630 with atemplate 610 having indentations 612 as previously described, as shownin FIG. 14a. After the deposition of the barrier layer 1302, the carrieris then mounted on a spin coating apparatus and coated with anadditional layer 1440 of a polymer photoresist, with the result shown inFIG. 14b. This is then partially etched so that the indentations in thetemplate 612 are now uniformly filled with the remaining portions of thephotoresist 1442, while the metal layer 1302 is exposed on the regionsof the template that correspond to the etched portions of the master600, as illustrated in FIG. 14c.

[0101] In subsequent processing steps, the carrier 630 with thesephotoresist portions 1442 filling indentations 612 in the template 610is aligned with a substrate 100 that has been partially manufactured andcoated with a layer of material 130 to be patterned, as shown in FIG.14d. These are then brought together in close proximity and pressedtogether. Layer 130 may be coated with an additional layer of material1462 to promote adhesion. The carrier is then removed, with the resultshown in FIG. 14e.

[0102] The substrate 100 with layer 130 and template 610 is thenprocessed in such a manner that the template dissolves, leaving only theportions of the photoresist 1442 on the surface of the layer 130 to beprocessed, as shown in FIG. 14f. This acts just as the portions ofresist 652 in the previously described embodiments of the invention forthe subsequent processing ot the substrate 100, to produce the resultshown in FIG. 14g, where portions 132 of the layer 130 remain.

[0103] It is clear that this additional processing can also comprise thecreation of entire portions of nanostructures for microdevices, as longas a suitably reliable transfer mechanism is developed. In this case,the material deposited can be a much thicker layer, and additionalprocessing steps can also be carried out as well.

[0104] Although such a layer can be fabricated entirely by sputteringtechniques, another approach is to use a thin layer of sputtered metalas a seed layer, and then perform electroplating techniques to create auniform film. Such electroplating techniques are useful with copper,aluminum, and gold seed layers.

[0105] One advantage that this technique has over other fabricationtechniques for layers of microdevices is that the creation of thisindividual layer is independent of the layers that normally precede itin the fabrication process. This allows additional processing of thislayer, and especially processing that might be incompatable withprevious processing steps for the device, to be an option at this point.

[0106] Such optional processing can comprise an annealing step for ametal, sputtering of material mixtures for specific properties, creationof multiple layers with dimensions controlled for their anti-reflectiveoptical properties, or the creation of a sequence of proteins for abiochip array. With the suitable choice of template and carriermaterial, processing at temperatures or under conditions not toleratedby the previously fabricated device layers can be done with impunity, aslong as the process is compatible with the disposable template material.

[0107] This is illustrated in FIG. 15. In this case, if patternsequivalent to the master 600 of the previous example is to be achieved,the template 1510 must actually be inverted, that is, having raisedareas 1512 corresponding to the indentations 612 of the previoustemplates 610.

[0108] A thin layer 1501 of the material to be processed is created fromby sputtering from a target 1590 made from that material, as shown inFIG. 1Sa. This is subsequently electroplated to form the thicker layer1502 shown in FIG. 15b. Additional processing steps can also be used toobtain a suitable deposit of the desired material.

[0109] Typically, this is then coated with a layer of a polymer 1540,which is then processed by etching or polishing to expose only theraised portions 1512 of the film 1502, while leaving leftover material1542 from the polymer film 1540 in the indentations, with the resultshown in FIG. 15c. The structures 1512 are essentially pre-fabricatedlayer of nanostructures that would normally have been created as thestructures 132 on a substrate 100. This prefabricated structure is thenstored until needed.

[0110] After a substrate with preprocessed layers 100 has reached thepoint in its manufacture where this layer is required, the template 1510with nanostructures 1512 and carrier 630 is removed from storage andaligned with the substrate 100, as shown in FIG. 15d. An adhesivecoating 1562 on the substrate 100 may be used for better attachment ofthe nanostructures 1512 on the template. The carrier and template 1510are then brought into close proximity and pressed together, as shown inFIG. 15e. The carrier is then removed, with the result shown in FIG.15f.

[0111] The template is then dissolved, leaving only the polymer and themetal. Subsequent processing can also remove the polymer material andthe excess portion of layer 1502, leaving only the portions 1532 of thatcorrespond to the nanostructures desired in the device. These would, forexample, correspond in size and shape to the structures 132 shown in theother figures.

[0112] An alternative process is shown in FIG. 16. Here, a thin layer1601 of the material to be processed is created from by sputtering froma target 1590 made from that material, as shown in FIG. 16a. This issubsequently electroplated to form the thicker layer 1602 and coatedwith a polymer 1642 to fill the indentations 612 as shown in FIG. 16b.This filling can be achieved by overfilling and etching or polishing thefilm, although other planarization techniques will be known to thoseskilled in the art. Additional processing steps can also be used toobtain a suitable deposit of the desired material.

[0113] This structure can then be further polished or etched to removeall but the portions 1632 of film 1602 that filled indentations 612,with the result shown in FIG. 16c. The structures 1632 are essentiallypre-fabricated layer of nanostructures that would normally have beencreated as the structures 132 on a substrate 100. This prefabricatedstructure is then stored until needed.

[0114] After a substrate with preprocessed layers 100 has reached thepoint in its manufacture where this layer is required, the template 610with nanostructures 1632 and carrier 630 is removed from storage andaligned with the substrate 100, as shown in FIG. 16d. An adhesivecoating 1660 on the substrate 100 may be used for better attachment ofthe nanostructures 1632. The carrier 630 and template 610 are thenbrought into close proximity and pressed together. The carrier 630 isthen removed, with the result shown in FIG. 15e.

[0115] As a final step, the substrate 100 and template 610 withnanostructures 1632 are processed so that the template 610 dissolves,leaving only the nanostructures 1632 in specific locations on thesubstrate 100. This corresponds to the structures 132 formed on thesubstrate 100 in other processing sequences disclosed in thisapplication.

[0116] Although we have originally conceived this as a technique for theprefabrication of layers or nanostructures for integrated circuits, thiscan apply to any technology which requires a patterning or lithographictechnique. For integrated optical applications, certain dopants foraltering fused silica waveguides may be pre-patterned and placed on thetemplate. For biochip applications, certain proteins or DNA strands withspecific sequences may be attached to the template and stored.

[0117] Storage of the Template

[0118] Once the material structure of the layer has been created on thetemplate, it can be stored until it is needed. Although this may be onlya few minutes, creating inventories of prefabricated device layers canavoid the queuing problems associated with “traffic jams” in waferfabrication, and template and carrier properties, as well as the storageenvironment, should be chosen for chemical stability, as well as tominimize contamination from outgassing, to reduce physical deformationfrom temperature fluctuations, and to generally preserve the material onthe template and carrier indefinitely.

[0119] Typically, the template will be enclosed in a sealed container,with controls for temperature, humidity, atmospheric content andpressure, and other variables controlled with the goal of maintainingmechanical and chemical integrity of the template and the structuresfabricated on it.

[0120] The template or replicated structure may also be adhered,frontside down, to a glass or silicon disc as part of the storageprocess. The disc provides a more rigid support and can be utilizedwithin a typical bonding or aligning tool as part of the transferprocess. The adhesive in this case may be a water soluble glue, forexample, such as polyvinyl alcohol. This adhesive would permit theeffect separation of the replicated pattern from the hard support duringthe transfer procedure. The solid structure may then be placed into thesolid container for transportation.

[0121] The template or replicated structure may also be adhered,backside down, to a glass or silicon disc as part of the storageprocess. This would allow the components to be faceside up during thetransfer process.

[0122] It may also be desirable to dice the template into individualcomponents or chips as part of the storage procedure. The dicing processenables more precise placement of the fabricated piece during thetransfer to the final substrate.

[0123] Transfer of the Nanostructures to the Substrate.

[0124] Once there is a substrate that requires the transfer of theparticular pattern replicated on the carrier, the suitable carrier isremoved from storage. The surface of the substrate is prepared, ifnecessary, with a suitable adhesion promoter layer 1462 or 1562 madefrom a suitable material such as cyanoacrylate ester. This can be doneusing a simple deposition technique, such as applying drops of liquidonto the surface from a nozzle, or using a more uniform spin coatingtechnique. Other adhesive materials, such as epoxies, acrylics,polyurathanes, photoresist, polyimides, low-k dielectrics, silicondioxide, aluminum oxide, PZT, P(L)ZT, Ruthenium oxide, barium titanate,barium strontium titanate, cadmium oxide, hafnium oxide, indium tinoxide, lead titanate, lead zirconate, tantalum pentoxide, titaniumoxide, tungstun oxide, zinc oxide, FSG, HSQ, HOSP, SILK, FEARE, PAE-2,probromide, paralene, PTFE, xero-gel, nano glass, andbizbenzocyclobutane, can also be used. When transferring nanostructuresthemselves instead of a pattern, some residue of this adhesion layerwill typically remain between the substrate and the nanostructures, socare must be taken to insure that this residue is compatible with thematerial being transferred, and that the desired properties (e.g.electrical contact, etc.) of the interface be maintained.

[0125] Actual transfer of the patterned layer, or of the nanostructuresthemselves from the carrier to the substrate can occur in a number ofways. Pressure can be uniformly applied from one side, or pressure canstart from one corner and be successively applied over the surface toinsure air bubbles are not trapped between the carrier and substrate.Pressure can be intermediate or pressure can be applied and held forsome period of time. High pressure may be required to insure goodcontact and uniformity. Adhesives that bind with pressure can be used,with the suitable application of pressure. Adhesives that bind with heatcan be used, with the suitable application of heat. Adhesives that bindwith UV photoexposure or curing can be used, along with the suitableapplication of UV exposure.

[0126] Once this step is finished, the template will adhere to thesubstrate, and the carrier itself can be removed. Because the patterningmaterial (e.g. gold and polymer for our example) remains attached, thetemplate can now be removed, leaving these other atructures attached tothe substrate. For our example of PVA as a template material, this canbe accomplished by simply dissolving the PVA from the surface withpurified water. For other template materials, other solvents may besuitable. Additional steps of mild abrasion or wiping may also be usedto selectively remove the template material, while leaving behind themetal and polymer combination.

[0127] Now that a patterned structure has been placed on the surface ofthe substrate, subsequent processing steps of deposition, etching,doping, or other chemical treatments can take place just as they wouldin any other printing technique.

[0128] Additional methods of adhesion can be deployed from the area ofwafer bonding. Some methods include the thermal fusion of metal to metalor anodic bonding. In the case of gold barrier layer contacting thesilicon surface. An initial adhesion of the PVA-metal layer is achievedby long-range forces. After the PVA is dissolved, the material structuremay then be heated to high temperature to form a eutectic bond betweenthe metal and silicon surface.

[0129] Another method involves directly heating a metallic interfacebetween the template and substrate using an energetic laser beam. Thisforms a weld between the template and substrate upon cooling.

[0130] When the nanostructure itself has been fabricated on the templateand transferred the adhesive layer on the substrate must be carefullychosen so that electrical properties are not impaired and goodelectrical contact with the substrate is achieved. Care must also betaken to align all the overlapping structures exactly. Although thealignment and transfer of several thousand or even millions ofpre-fabricated metal nanostructure wires may be hard to achieve withgood repeatability, there are applications (the repair of a single IC,for example), where the placement of a single nanowire can add value foran IC.

[0131] It will also be understood that the metal coated template orpolymer coated template can also be used as a master itself insubsequent processes, including those found in the prior art nanoimprinttechniques. In this case, the template is not destroyed, but againreplicated, and the replicas can be used and destroyed without damage tothe template.

[0132] Alignment of the Carrier and Substrate

[0133] To align and transfer the smooth template onto the substrate,standard wafer aligners and bonders are useful. Examples of commerciallyavailable aligner equipment that can be used to transfer the patternonto the substrate include the EVG620 sold by the EV Group of Austria.Bonding equipment that can be coupled include the EVG520 bonder soldalso by the EV Group. In this approach, alignment marks are recorded ofthe template. The gold or organic coating relief image createssufficient contrast to determine the position of the template relativeto the substrate. After recording the relative positions, servosmanipulate the substrate to align and contact the template. A vacuumassisted bond helps to remove air bubbles between the template andsubstrate.

[0134] Additional Processing Options.

[0135] Further processing steps may be added to the above sequence toform specialized structures. It is possible to form a latent image ontop of the PVA contoured metal surface replica prior to removal from themaster surface.

[0136] It is also possible to develop the latent image pattern on thecontoured metal surface. Subsequently, additional PVA solution may bespin-coated onto the developed pattern to form a multilayer structure ofmetal and organic material. The combined structure may then be removedfrom the surface of the master using the aforementioned techniques. Thestructure may then be transferred onto a second substrate or useddirectly.

[0137] While specific materials, coatings, carriers, substrates, andprocess steps have been set forth to describe and exemplify thisinvention and its preferred embodiment, such descriptions are notintended to be limiting. Modifications and changes may be apparent tothose skilled in the art, and it is intended that this invention belimited only by the scope of the appended claims.

I claim exclusive property and privilege over the following:
 1. A methodfor pattern formation comprising creating a replica of a master pattern;transferring the replica onto a substrate comprising material to bepatterned, and destroying the replica while it is in contact with thesubstrate.
 2. The method of claim 1, in which the replica can bedissolved in a solvent, and the step of destroying comprises dissolvingthe replica in said solvent.
 3. The method of claim 2, in which thereplica is fabricated from polyvinyl alcohol (PVA), and the solvent isan aqueous solution.
 4. The method of claim 1, in which the step ofdestroying comprises etching the replica.
 5. The method of claim 1, inwhich the step of creating the replica comprises spin coating of thereplica material from a solution onto the substrate.
 6. The method ofclaim 1, in which the step of creating the replica comprises casting aliquid polymer on the master.
 7. The method of claim 5 or 6, in whichthe step of creating the replica also comprises drying the liquidpolymer.
 8. The method of claim 5 or 6, in which the step of creatingthe replica also comprises UV curing of the polymer.
 9. The method ofclaim 5 or 6, in which the step of creating the replica also comprisesheating the polymer.
 10. The method of claim 1, comprising an additionalstep of removing the replica from the master, and attaching the replicato a carrier.
 11. The method of claim 10, in which the carrier is coatedwith a material to promote adhesion to the replica.
 12. The method ofclaim 10, in which the replica is coated with a material to promoteadhesion to the carrier.
 13. The method of claim 11 or 12, in which theadhesion promotion material comprises polyvinyl alcohol (PVA).
 14. Themethod of claim 11 or 12, in which the adhesion promotion materialcomprises the same material as the replica.
 15. The method of claim 10,further comprising the additional step of storing the replica andcarrier.
 16. The method of claim 15, in which the storage environment iscontrolled for temperature.
 17. The method of claim 15, in which thestorage environment is controlled for humidity.
 18. The method of claim15, in which the storage environment is controlled for pressure.
 19. Themethod of claim 15, in which the atmosphere of the storage environmentis controlled for chemical composition.
 20. The method of claim 15, inwhich the replica is inserted into a protective package during storage.21. The method of claim 10, in which the step of transferring comprisesaligning the carrier to the substrate.
 22. The method of claim 10, inwhich the step of transferring comprises touching the replica againstthe substrate.
 23. The method of claim 22, in which the step oftransferring comprises pressing the replica against the substrate. 24.The method of claim 22, in which the substrate is coated with a materialto promote adhesion of the replica.
 25. The method of claim 24, in whichthe adhesion promotion material comprises a cyanoacrylate ester.
 26. Themethod of claim 22, in which the substrate is coated with a deformablematerial.
 27. The method of claim 26, in which the deformable materialis a polymer.
 28. The method of claim 26, in which the deformablematerial is a photoresist.
 29. The method of claim 26, in which thedeformable polymer is the material to be patterned.
 30. A method forforming a pattern on a substrate, comprising: spin coating a polymerfilm onto a master comprising topographic patterns, such that thepolymer form replicates the topographic structures of the master,transferring the replica to a carrier, aligning the carrier with replicato a substrate which comprises a material to be patterned, transferringthe replica to the substrate, in a manner that the replica transfers thetopographic pattern of the replica to the material to be transferred,and dissolving the replica wile it is attached to the substrate.
 31. Themethod of claim 30, in which the polymer used to form the replica ispolyvinyl alcohol.
 32. The method of claim 30, comprising an additionalstep of storing the carrier with replica for some time beforetransferring the replica to the substrate.
 33. The method of claim 10,comprising additional steps of forming a barrier layer on the replicaafter the replica is removed from the master.
 34. The method of claim33, in which the material for the barrier layer comprises gold.
 35. Themethod of claim 34, in which the step of forming the barrier layercomprises deposition of gold on the replica using a sputtering process.36. The method of claim 33 or 35, comprising an additional step offorming an additional barrier layer of polymer on the replica.
 37. Themethod of claim 36, in which the polymer barrier layer is subsequentlyetched.
 38. A method for forming a patterned layer of material on asubstrate, comprising preparation of a master with topographicstructures in a layout that corresponds to the desired pattern, coatingthe master with a polymer film, curing the polymer film in a manner thatforms topographic structures in the film that replicate at least aportion of the topographic patterns of the master, transferring thepolymer film replica from the master to a carrier, processing thereplica with a sequence of steps that leave materials on certainportions of the topographic structures of the replica, corresponding tothe desired pattern, aligning the replica to a substrate, bringing thereplica and the substrate into close proximity, and transferring thematerials from said certain portions on the replica to the substrate.39. The method of claim 38, in which the sequence of steps leavingmaterials comprises sputtering a material.
 40. The method of claim 39,in which the composition of the material is selected from the groupcontaining gold, platinum, palladium, copper, aluminum, chromium,nickel, silicon, germanium, tungsten, silver, yttrium, barium, cobalt,and carbon.
 41. The method of claim 38, in which the sequence of stepsleaving materials comprises electroplating.
 42. The method of claim 41,in which the sequence of steps comprises sputtering a layer of material,followed by a step of electroplating using additional material ofsimilar composition as said layer of material, such that the dimensionsof the layer of material increase.
 43. The method of claim 38, in whichthe sequence of steps leaving materials comprises spin coating a secondpolymer.
 44. The method of claim 43, in which the second polymer is aphotoresist.
 45. The method of claim 44, in which the sequence of stepsadditionally comprises exposure to ultraviolet light.
 46. The method ofclaim 45, in which the sequence of steps additionally comprisesdeveloping the photoresist.
 47. The method of claim 38, in which thesequence of steps leaving materials comprises an etch process.
 48. Amethod for forming a set of microstructures for an electronic device,comprising forming a patterned layout on a carrier corresponding toportions of the microstructures, processing the carrier to create theset of structures of the electronic device, and transferring thefabricated set of structures from the carrier to a substrate.
 49. Amethod for forming a set of nanostructures for a microdevice, comprisingforming a patterned layout on a carrier corresponding to portions of themicrodevice, processing the carrier to create the set of nanostructuresof the microdevice, and transferring the fabricated set ofnanostructures from the carrier to a substrate.
 50. A method for forminga set of structures for a MEMS device, comprising forming a patternedlayout on a carrier corresponding to portions of the MEMS device,processing the carrier to create the set of structures of the MEMSdevice, and transferring the fabricated set of structures from thecarrier to a substrate.
 51. A method for forming a set of structures fora photonic device, comprising forming a patterned layout on a carriercorresponding to portions of the photonic device, processing the carrierto create the set of structures of the photonic device, and transferringthe fabricated set of structures from the carrier to a substrate.
 52. Amethod for forming a set of structures for a biochip, comprising forminga patterned layout on a carrier corresponding to portions of thebiochip, processing the carrier to create the set of structures of thebiochip, and transferring the fabricated set of structures from thecarrier to a substrate.
 53. An integrated circuit, in which at least aportion of a layer of the device has been fabricated by a processcomprising: forming a patterned layout on a carrier corresponding toportions of the microstructures of the integrated ciruit, processing thecarrier to create the set of structures of the integrated circuit, andtransferring the fabricated set of structures from the carrier to asubstrate comprising another portion of the integrated circuit.
 54. AMEMS device, in which at least a portion of a layer of the device hasbeen fabricated by a process comprising: forming a patterned layout on acarrier corresponding to portions of the microstructures of the MEMSdevice, processing the carrier to create the set of structures of theMEMS device, and transferring the fabricated set of structures from thecarrier to a substrate comprising another portion of the MEMS device.55. A photonic device, in which at least a portion of a layer of thedevice has been fabricated by a process comprising: forming a patternedlayout on a carrier corresponding to at least a portion of the photonicdevice, processing the carrier to create the set of structures of thephotonic device, and transferring the fabricated set of structures fromthe carrier to a substrate comprising another portion of the photonicdevice.
 56. A superconducting device, in which at least a portion of alayer of the device has been fabricated by a process comprising: forminga patterned layout on a carrier corresponding to at least a portion ofthe superconducting device, processing the carrier to create the set ofstructures of the superconducting device, and transferring thefabricated set of structures from the carrier to a substrate comprisinganother portion of the superconducting device.
 57. A biochip, in whichat least a portion of a layer of the biochip has been fabricated by aprocess comprising: forming a patterned layout on a carriercorresponding to at least a portion of the biochip, processing thecarrier to create the set of structures of the biochip, and transferringthe fabricated set of structures from the carrier to a substratecomprising another portion of the biochip.
 58. A article of manufactureproduced by a process comprising spin coating a PVA film onto a mastercomprising topographic patterns, and removing the film from the master.59. The article of claim 58 produced using an additional step comprisingattaching the PVA film to a carrier.
 60. The article of claim 58produced using an additional step comprising depositing a material onthe surface of the PVA film.
 61. The article of claim 60, in which thedeposited material is selected from the group containing gold, platinum,palladium, copper, aluminum, chromium, nickel, silicon, germanium,tungsten, silver, yttrium, barium, cobalt, and carbon.
 62. The articleof claim 58 produced using an additional step comprising coating apolymer on the surface of the PVA film.
 63. The article of claim 60produced using an additional step comprising coating a polymer on thesurface of the deposited material.
 64. An article of manufactureproduced by a process comprising forming a film of PVA by a coating amaster comprising topographic structures, removing the PVA film, coatingat least a portion of the coated PVA film with a polymer.
 65. An articleof manufacture produced by a process comprising forming a film of PVA bya coating a master comprising topographic structures, removing the PVAfilm, depositing a layer of metal on at least a portion of the PVA film,and coating at least a portion of the metal coated PVA film with apolymer.
 66. The article of claim 65, in which the metal is gold.